This invention relates to the art of induction heating apparatus and, more particularly, to improved apparatus for inductively heating surfaces of non-rotating workpieces.
It is of course well known to inductively heat and quench the surfaces of workpieces by rotating the workpieces relative to a stationary inductor coil. Often, however, rotation of the workpiece is not easily achieved, or is impractical, such as for example where the surfaces of the workpieces to be heated are eccentric with respect to the axis of the workpiece and/or where the heat treating operation is at one stage of a automated multi-stage machine wherein the workpiece is held by stationary fixtures against rotation while operations are performed thereon by rotating cutting tools and the like. Accordingly, it becomes desirable in these and other situations to achieve heat treating by rotating the inductor relative to the workpiece. Rotatable inductor arrangements have been provided heretofore for the latter purpose, but such prior arrangements have included the use of slip rings or mercury wetted contacts to convey the high currents from the power source to the inductor coil. Such arrangements are inefficient with respect to conducting high currents, are difficult to maintain and are structurally complex. Additionally, mercury is a toxic substance whereby its use in such arrangements is hazardous to personnel operating the equipment.